CALIFORNIA 
AGRICULTURAL  EXTENSION  SERVICE 

CIRCULAR  22 
December,  1928 


Thinning  Sugar  Beets 


W.W.  ROBBINS 


PUBLISHED  BY 

THE  COLLEGE  OF  AGRICULTURE 
UNIVERSITY  OF  CALIFORNIA 


Cooperative  Extension  work  in  Agriculture  and  Home  Economics,  College  of  Agriculture, 
University  of  California,  and  United  States  Department  of  Agriculture  cooperating.  Dis- 
tributed in  furtherance  of  the  Acts  of  Congress  of  May  8  and  June  30,  1914.  B.  H,  Crocheron, 
Director,  California  Agricultural  Extension  Service. 


UNIVERSITY  OF  CALIFORNIA  PRINTING  OFFICE 

BERKELEY,  CALIFORNIA 

1928 


Digitized  by  the  Internet  Archive 

in  2011  with  funding  from 

University  of  California,  Davis  Libraries 


http://www.archive.org/details/thinningsugarbee22robb 


THINNING  SUGAR  BEETS 

W.  W.  ROBBINSi 

One  of  the  most  readily  controllable  operations  in  growing  sugar 
beets,  and  one  which  determines  to  such  a  very  large  degree  the  final 
yield,  is  that  of  thinning.  Under  ordinary  conditions,  proper  thin- 
ning is  one  of  the  most  important  steps  in  securing  a  good  stand  of 
sugar  beets.  There  are,  of  course,  various  other  important  consider- 
ations which  the  grower  must  bear  in  mind,  in  order  to  produce  sugar 
beets  successfully ;  but  they  can  not  all  be  discussed  here. 

This  circular  aims  to  emphasize  the  necessity  of  exercising  care  in 
the  thinning  of  beets ;  it  points  out  the  need  for  instruction  and  super- 
vision of  the  labor;  it  discusses  the  time  to  thin,  proper  spacing,  the 
value  of  selecting  the  large  seedling,  the  influence  of  stand  on  yield, 
and  the  fundamental  reasons  for  the  different  practices  in  the  thin- 
ning operation. 

WHY   BEETS  ARE  THINNED 

The  beet  ' '  seed  ball, ' '  as  known  commercially,  is  a  corky  structure 
containing  from  one  to  five  true  seeds.  A  seed  ball  containing  several 
seeds  arises  when  the  flowers  are  in  clusters ;  in  this  case,  the  parts 
of  the  several  flowers  grow  together,  forming  a  several-seeded  mass, 
the  ''seed  ball."  If  a  flower  stands  by  itself  on  the  stem,  a  single- 
germ  beet  seed  is  produced.  In  an  ordinary  commercial  lot  of  seed, 
there  is  a  relatively  small  percentage  of  single-germ  seeds. 

It  will  be  seen  from  the  foregoing  description  that  when  one  beet 
seed  ball  is  planted  in  a  place,  from  one  to  five  plants  may  grow  from 
it.  These  young  plants  come  out  of  the  ground  so  close  together  that 
they  necessarily  compete  with  each  other  for  space  in  which  to 
spread  their  leaves  and  roots,  and  for  water  and  plant  nutrients.  If 
some  of  the  plants  were  not  removed,  there  would  be  insufficient 
nutrients  in  the  soil  to  support  their  best  growth ;  leaf  development 
would  be  hindered;  roots  would  be  small  and  twisted  about  each 
other;  and  the  returns  in  tons  of  roots  and  sugar  per  acre  would  be 
unprofitable.  In  thinning,  the  object  is  to  leave  the  largest  and 
healthiest  seedlings,  and  these  so  distributed  evenly  in  the  row  as  to 
permit  their  normal  development.  Also,  in  thinning,  weeds  in  the 
rows  and  in  places  which  the  cultivator  cannot  reach  should  be 
removed. 


1  Professor  of  Botany  and  Botanist  in  the  Agricultural  Experiment  Station. 


CALIFORNIA  AGRICULTURAL  EXTENSION   SERVICE  [CiRC.  2^ 


AT   WHAT    AGE    SHOULD    BEETS    BE    THINNED? 

It  is  the  general  experience  of  beet  growers  that  the  highest  yields 
are  secured  by  thinning  beets  when  they  have  attained  a  stage  of 
development  indicated  by  the  presence  of  two  to  four  true  leaves. 
In  a  seedling  of  this  age,  there  will  be,  in  addition  to  the  two  to  four 
true  leaves,  two  seed  leaves.  Thinning  later,  when  the  plants  have 
as  many  as  eight  true  leaves,  may  result  in  injury  to  the  plants  that 
are  left.  In  the  first  place,  by  postponement  of  thinning,  the  plants 
have  been  crowded  to  such  an  extent  as  to  be  hindered  in  their  growth ; 
and  secondly,  the  root  system  has  attained  a  growth  that  is  easily 
disturbed.  The  smaller  the  beets  when  thinned,  the  less  their  growth 
will  be  checked. 

However,  very  early  thinning  may  be  followed  by  a  relatively 
great  loss  of  beets.  The  reason  for  this  is  that  the  weakest  seedlings 
often  succumb  to  seedling  diseases,  the  greatest  mortality  occurring 
before  the  plants  have  developed  the  second  i^air  of  leaves.  Normally, 
there  is  some  natural  elimination  of  the  weak  plants,  and  time  should 
be  allowed  for  this  natural  weeding-out  to  take  place  before  thinning 
is  done.  Otherwise,  unknowingly,  the  weak  or  diseased  seedlings 
may  be  left. 

A  delay  in  thinning  may  be  justified  when  the  crop  is  exposed  to 
insect  injury,  as  for  instance,  when  the  soil  is  infested  with  wire 
worms,  or  centipedes,  which  threaten  destruction  of  the  stand  after 
thinning. 

There  are  available  some  results  of  experiments  on  early  and  late 
thinning.  In  one  case,  beets  thinned  when  they  had  two  to  four  leaves 
yielded  1%  tons  more  per  acre  than  beets  thinned  when  they  had 
eight  to  ten  true  leaves;  and  3%  tons  more  per  acre  than  beets 
thinned  when  they  had  twelve  to  fourteen  true  leaves. 

The  agricultural  department  of  the  Great  Western  Sugar  Com- 
pany reports  the  following  results: 

1914 — Beets  blocked  and  thinned  when  16  days  old  produced 
1596  pounds  beets  and  167  pounds  sugar  more  per  acre  than  beets 
blocked  and  thinned  when  31  days  old  (delay  of  15  days). 

1923 — Beets  blocked  and  thinned  when  25  days  old  produced  845 
pounds  beets  and  91  pounds  sugar  more  per  acre  than  beets  blocked 
and  thinned  when  32  days  old  (delay  of  7  days). 

1924 — A  delay  of  14  days  reduced  the  yield  2744  pounds  beets 
and  645  pounds  sugar  per  acre. 


1928]  THINNING    SUGAR    BEETS  5 

Thinning  beets  is  an  operation  which  should  be  started  promptly, 
and  pushed  to  as  quick  a  conclusion  as  possible  while  soil  and  weather 
conditions  are  favorable.  Too  frequently,  because  of  delay,  the  beets 
in  a  part  of  the  field  become  so  large  that  they  suffer  from  the 
thinning. 

The  above  statements  concerning  the  age  at  which  beets  should 
be  thinned,  apply  particularly  to  sediment  soils.  Although  there  are 
no  experimental  data,  it  is  the  observation  of  certain  growers  on  peat 
lands,  that  thinning  can  be  delayed  much  longer  on  such  soils  than 
on  sediment  soils,  without  injury  to  the  beets.  They  even  go  farther 
and  state  that  thinning  should  be  delayed.  It  is  claimed  that  unless 
the  young  beets  on  peat  soils  have  a  well-established  root  system  at 
thinning  time,  the  roots  of  the  seedlings  left  are  likely  to  dry  out  in 
the  soil  which  has  become  loosened  as  a  result  of  its  distarbance  in 
thinning.  Moreover,  it  appears  that  there  is  less  twisting  of  roots  of 
closely  adjacent  plants  in  loose  soils  than  there  is  in  heavier  soils. 


SPACING    BEETS 

The  basic  consideration  in  the  distribution  of  sugar  beets  is  the 
soil  volume  in  which  the  plants  absorb  water  and  plant  nutrients.  It 
is  obvious  that  the  sjiacing  in  the  row  can  be  somewhat  closer  when 
the  rows  are  22  inches  apart  than  when  they  are  18  inches  apart. 
Moreover,  a  rich  soil  will  support  more  beets  per  unit  area  than  an 
impoverished  soil.  No  iron-clad  rule  can  be  laid  down,  specifying 
the  distance  beets  should  be  thinned,  which  would  cover  all  the  various 
conditions  under  which  sugar  beets  are  grown.  However,  experience 
and  experimentation  have  taught  that,  on  the  average  and  on  most 
soil  types,  216  square  inches  per  beet  gives  maximum  yields.  This 
is  equivalent  to  a  12-incli  stand  in  the  row  with  rows  18  inches  apart, 
or  to  a  10.8-inch  stand  with  rows  20  inches  apart.  Crowding  beets 
reduces  the  amount  of  light  coming  to  the  individual  plant,  and  also 
reduces  the  soil  volume  in  which  the  plants  feed.  In  unnecessarily 
wide  spacing,  the  land  is  not  working  to  its  full  capacity.  It  should 
be  stated  at  this  point  that  a  wide  stand  reduces  the  sugar  per  cent 
and  a  close  stand  elevates  the  sugar  per  cent.  If  the  beet  plant  has 
ample  room  in  which  to  grow  and  develop,  it  becomes  large  at  the 
sacrifice  of  sugar  per  cent;  if  it  is  crowded  by  close  spacing,  its  size 
is  reduced  but  the  sugar  per  cent  is  relatively  high. 

In  tables  1  and  2  are  given  figures  from  the  Colorado  and  Nebraska 
districts  of  the  Great  Western  Sugar  Company,  covering  the  1925 


CALIFORNIA  AGRICULTURAL  EXTENSION  SERVICE 


[CiRC.  22 


crop,  which  show  that  a  spacing  in  the  row,  wider  than  12  inches, 
results  in  loss  of  yield.  (In  these  tables,  the  spacing  given  was 
determined  at  harvest  time,  and  it  does  not  represent  a  spacing 
secured  at  thinning.) 

TABLE  1 

Effect  of  Spacing  on  Yield,  Colorado,  1925 


Average 
spacing 
in  inches 

Weights 
of  beets 
in  ounces 

Tons 

of  beets  to 

the  acre 

Number  of 
contracts 

51  1 

30.2 

5  79 

194 

33.8 

30.3 

8.80 

451 

26.7 

30.4 

11.20 

917 

21.9 

30.1 

13.47 

1243 

18.8 

28.4 

14.83 

881 

16.3 

26.9 

16  21 

360 

14  4 

24.7 

16  80 

85 

11.9 

23.1 

19.10 

31 

Avg.  22.2 

30.4 

13.38 

TABLE  2 


Effect  of 

Spacing  on 

Yield, 

Nebraska,  1925 

Average 
spacing 
in  inches 

Weights 
of  beets 
in  ounces 

Tons 

of  beets  to 

the  acre 

Number  of 
contracts 

51  5 

35  2 

6.70 

16 

33.9 

34.7 

10 

05 

47 

26  5 

34  9 

12 

95 

194 

21  7 

33.9 

15 

35 

511 

18.7 

32.9 

17 

28 

569 

16  3 

31  0 

18 

60 

212 

14.6 

29.1 

19 

58 

29 

11  5 

23.4 

19 

96 

9 

Avg.  20.0 

33.7 

16.47 

Let  us  do  some  computing  as  to  the  influence  of  stand  upon  the 
yield  of  beets.  Of  course,  we  know  that  many  of  our  plans  fall  short 
of  realization,  but  it  is  only  by  understanding  what  the  possibilities 
are,  that  we  can  work  intelligently  to  realize  the  ideal. 

With  rows  18  inches  apart,  there  are  29,040  feet  of  row  in  an  acre. 
If,  on  the  average,  there  is  one  beet  to  every  12  inches,  there  will  be 
29,040  beets  per  acre.  If  the  beets  average  24  ounces,  the  yield  will 
be  21.7  tons.  If  there  is  one  beet  every  14  inches,  there  will  be  24,891 
beets  per  acre,  and  the  yield  (on  the  basis  of  the  beets  averaging  24 


1928] 


THINNING    SUGAR    BEETS 


ounces  each)  will  be  18.7  tons.  If  there  is  one  beet  every  16  inches, 
there  will  be  21,180  beets  per  acre,  and  the  yield  (on  the  basis  of  the 
beets  averaging  24  ounces  each)  will  be  15.8. 

It  is  known  that  spacing  influences  the  size  of  beets.  Naturally, 
wide  spacing  in  the  row  or  between  the  rows  makes  for  larger  beets 
than  close  or  narrow  spacing.  However,  it  cannot  be  assumed  that 
if  the  stand  is  increased  from  12  inches  to  16  inches,  for  example. 


TABLE  3 

Yields    with   Different    Spacing    and    Different   Weights    of    Beets 
(Based  on  18  Inches  Between  Rows) 


Ounces 


16. 
17. 

18. 
19. 
20. 
21. 
22 
23 
24 
25 
26 
27 
28 
29 
30 
31 
32 


Spacing  in  rows  (inches) 


12 

14.52 
15  43 
16.43 
17.24 
18.15 
19.06 
19.97 
20.87 
21.78 
22.69 
23.60 

24  50 

25  41 
26.30 
27.20 
28.12 
30.04 


13 

13  40 

14  24 

15  08 
15.91 
16.75 
17.59 
18.43 
16.26 
20.10 
20  94 
21.78 
22  61 
23.45 
24.29 
25.12 
25.96 
26.87 


14 


14  25 
13  23 
14.00 
14.78 

15  56 

16  43 
17.12 
17,89 
18  67 
19.45 
20  23 
21.00 
21.78 
22.56 
23.34 
24  12 
24.87 


15 


15  08 
12.34 

13  07 
13.79 

14  52 
15.25 
15.97 

16  70 

17  42 
18.15 

18  88 
19.60 
20  33 
21.05 
21.78 
22  51 
23.23 


16 

10,89 

11  57 

12  25 
12,93 

13  61 

14  29 

14  97 

15  65 

16  33 

17  01 
17.69 

18  37 

19  05 
19.73 

20  42 
21.09 
21.78 


17 


10  24 

10  89 

11  53 

12  17 

12  81 

13  45 

14  09 

14  73 

15  37 

16  01 
16.65 
17.29 
17.93 
18  57 
19.22 
19.86 
20.49 


18 


9  68 
10.29 
10.89 
11.50 

12  10 
12.71 

13  31 

13  92 

14  52 

15  13 
15.73 
16.34 
16.94 
17  55 
18.15 
18.73 
19.36 


19 


9.17 
9.74 

10  31 
10.89 

11  46 
12,03 

12  61 
13,18 

13  75 
14,33 

14  90 
15,47 
16  04 
16.62 
17.19 
17.76 
18.34 


20 


8.71 
9.26 
9.80 
10.35 
10.89 

11  43 
11.98 

12  52 

13  07 
13.61 
14.16 

14  17 
15.25 
15.79 
16.34 
16.88 
17.42 


the  beets  will  be  enough  larger  to  compensate  for  the  decreased  num- 
ber of  beets  to  the  acre.  Care  should  be  taken  to  secure  a  stand  of 
beets  rather  than  to  trust  in  luck  that  if  there  is  a  wide  stand,  the  beets 
will  be  sufficiently  large  to  make  up  for  the  fewer  beets  to  the  acre. 
High  yields  are  much  more  often  due  to  good  stands  than  to  oversized 
beets.  This  is  well  shown  in  the  yields  on  plots  at  the  University 
Farm  during  1928.  The  average  yield  of  six  different  varieties,  each 
of  four  replications,  was  28.5  tons  per  acre.  This  high  yield  was 
secured  even  though  the  average  weight  of  roots  was  but  1.9  pounds; 
but  the  average  number  of  beets  per  acre  was  29,330,  which  is  a 
splendid  stand. 

Table  3  shows  the  yield  of  beets  which  will  be  obtained  with  any 
particular  spacing,  and  average  weight  of  individual  beet  root. 

The  figures  (12-20)  across  the  top  of  the  table  refer  to  inches  in 
the  row,  and  the  figures   (16-32)   along  the  left  hand  side  refer  to 


8  CALIFORNIA  AGRICULTURAL  EXTENSION  SERVICE  [CiRC.  22 

ounces;  the  tonnage  corresponding  to  any  particular  spacing  and 
average  weight  of  beet  is  found  at  the  intersection  of  the  vertical  and 
longitudinal  columns.  For  example,  roots  averaging  20  ounces  and 
spaced  16  inches  in  the  row  will  yield  13.61  tons  per  acre. 

It  has  been  stated  that  when  the  rows  are  18  inches  apart,  the 
ideal  is  a  beet  every  12  inches,  and  when  the  rows  are  20  inches 
apart,  a  beet  approximately  every  11  inches.  This  is  possible  only 
when  the  germination  stand  is  very  good.  But  there  are  often  blanks 
or  ''misses"  in  the  germination  stand.  In  this  event,  there  should 
be  an  effort  to  make  up  for  these  by  spacing  the  beets  closer  imme- 
diately on  either  side  of  a  blank  space  in  the  row.  This  will  mean 
that  there  will  be  some  beets  6  or  8  inches  apart  in  the  row.  This 
practice  in  thinning  secures  a  larger  number  of  beets  to  the  acre, 
and  although  the  close  spacing  here  and  there  reduces  the  size  of 
the  individual  beets  which  are  crowded,  the  total  yield  per  acre  is 
increased.  The  method  of  thinning  just  described  is  particularly 
useful  in  fields  where  the  germination  stand  is  uneven,  or  w^here  there 
has  been  destruction  of  seedlings  by  disease  or  cold  weather. 

If  in  every  100  feet  of  row  there  were  two  blank  spaces,  and  there 
are  left  three  extra  beets  on  each  side  of  the  blank,  then  by  closer 
spacing,  there  would  be  six  extra  beets  in  every  100  feet  of  row.  If 
each  extra  beet  averages  IV2  pounds,  the  increase  would  be  1.17  tons. 

The  progressive  beet  grower  is  working  for  a  100  per  cent  stand. 
This  means  an  average  of  100  to  110  beets  in  every  100  feet  of  row, 
depending  upon  whether  the  rows  are  18  to  20  inches  apart.  Then 
the  land  is  working  to  full  capacity.  The  cost  of  cultivating  and 
irrigating  a  60  per  cent  or  a  75  per  cent  stand  is  just  as  great  as 
that  of  cultivating  and  irrigating  a  100  per  cent  stand.  A  poor  stand 
means  that  blank  spaces  are  being  cared  for  throughout  the  entire 
season. 

It  is  the  experience  of  growers  and  of  those  who  have  carefully 
studied  the  results  of  instructions  given  to  labor,  that  in  general,  the 
stand  left  by  the  thinner  is  usually  somewhat  wider  than  that  asked 
for.  For  example,  if  labor  is  instructed  to  leave  a  12-inch  stand 
where  it  is  possible  to  secure  such  a  stand,  one  may  expect  a  spacing 
of  13  or  14  inches ;  the  spacing  of  beets  left  after  thinning  is  usually 
wider,  seldom  ever  closer,  than  that  which  is  instructed  be  given. 

In  the  foregoing  discussion,  consideration  has  been  given  to  the 
spacing  which  is  usually  best  based  on  18  inches  between  rows.  How- 
ever, there  may  be  conditions  under  which  it  is  desirable  to  have  a 
greater  distance  between  rows.     In  such  cases,  the  distance  between 


1928]  THINNING    SUGAR    BEETS  9 

beets  in  the  row  can  be  less  than  12  inches.  For  example,  when 
rows  are  20  inches  apart,  a  spacing  of  10.8  inches  in  the  row  gives 
each  beet  as  much  soil  volume  as  when  the  rows  are  18  inches  apart 
and  the  spacing  in  the  row  is  12  inches. 


LEAVE    THE    LARGE    SEEDLING 

It  is  a  common  observation  that  there  is  great  variation  in  the  size 
and  vigor  of  the  different  seedlings  found  in  any  germination  stand. 
What  are  the  reasons  for  this?  In  the  first  place,  there  is  much 
variation  in  the  size  of  the  beet  seed  balls.  In  the  second  place,  the 
different  seeds  in  a  seed  ball  vary  considerably  in  size.  But  more 
important  than  the  size  of  the  seed  ball  or  of  the  seed,  is  the  vigor  of 
the  germs  or  young  plants  within.  For  example,  in  a  beet  ball  con- 
taining four  seeds,  the  actual  dry  weight  of  the  individual  germs, 
determined  just  as  they  make  their  appearance  at  germination,  may 
range  from  approximately  2  milligrams  to  3  milligrams.  That  this 
range  is  in  all  probability  due  to  a  difference  in  the  amount  of  reserve 
food  in  the  different  seeds  is  strongly  indicated  by  the  observation 
that  in  all  classes  of  seed  balls  the  weight  of  any  particular  germ  in 
a  ball  exceeds  that  of  any  other  germ  in  that  ball  which  makes  its 
appearance  at  a  later  time.  In  other  words,  in  a  seed  ball  which 
contains  more  than  one  seed,  the  strongest  germ  germinates  first. 
Consequently,  in  any  one  seed  ball,  containing  several  seeds,  one  germ 
is  stronger  and  more  vigorous  than  the  remainder.  Observation  bears 
out  the  conclusion  that  this  relative  difference  continues  throughout 
the  life  of  the  plant.  Evidently,  then,  with  similar  care,  the  large 
germ  becomes  the  large  beet,  and  the  small  germ  becomes  the  small 
beet.  The  runt  beet  plants  at  thinning  time  remain  runts,  just  like 
the  runt  pigs  in  the  litter.  This  fact  should  be  recognized  in  thin- 
ning, and  care  be  exercised  to  leave  the  large  seedling. 

In  one  case,  an  experimenter  selected  a  large  seed  ball  containing 
five  seeds.  The  five  germs  were  grown  under  similar  conditions.  The 
weights  (in  ounces)  of  the  five  different  individual  beets  at  harvest 
were  as  follows :  1.9,  5.8,  8.6,  16.4,  29.0.  These  figures  also  emphasize 
the  great  variation  that  exists  in  the  different  individuals  arising  from 
a  single  seed  ball. 

The  experiment  station  of  the  Great  Western  Sugar  Company  has 
for  a  number  of  years  been  making  a  comparison  of  the  development 
of  beets  produced  by  large  and  by  small  seedlings.  At  the  time  of 
thinning,  a  number  of  beets,  larger  than  the  average,  and  designated 


10  CALIFORNIA  AGRICULTURAL  EXTENSION   SERVICE  [CiRC.  22 

''large,"  were  selected.  They  were  given  the  same  culture  through- 
out the  season,  and  careful  measurements  were  made  throughout  the 
life  of  the  plants.     The  general  results  are  as  follows : 

(1)  The  large  seedling  develops  into  a  larger  beet  at  harvest  than 
does  the  small  one. 

(2)  The  percentage  of  beets  dying  is  usually  greater  among  those 
which  are  small  at  the  time  of  thinning  than  among  those  which  are 
large  at  thinning. 

(3)  The  total  sugar  of  beets  from  large  seedlings  slightly  exceeds 
that  of  beets  from  small  ones. 

(4)  The  per  cent  of  tops  in  terms  of  the  average  weight  of  beets 
at  harvest  is  smaller  in  the  case  of  beets  from  the  large  seedlings  than 
in  that  of  beets  from  the  small  seedlings. 

Tests  similar  to  the  above  were  conducted  for  two  successive  sea- 
sons (1926-27)  at  the  University  Farm,  Davis,  California.  In  both 
years,  the  yield  from  large  seedlings  was  approximately  35  per  cent 
greater  than  that  from  small  seedlings. 

It  would  take  a  number  of  pages  to  recite  even  briefly  the  experi- 
ences of  many  beet  growers  testifying  to  the  increased  yields  that 
have  resulted  from  leaving  the  large  seedlings  at  thinning.  Several 
specific  cases  are  here  given.  Reference  to  them  is  made  by  number, 
but  the  names  and  addresses  of  the  growers  may  be  secured  by  any 
one  who  wishes  to  learn  further  details  of  the  growing  operation. 

1.  A  2-acre  tract  thinned  by  the  owner,  who  took  pains  to  leave 
only  the  big  beets,  yielded  261^  tons  per  acre.  The  remainder  of  his 
tract,  737  acres,  was  thinned  in  the  ordinary  way,  without  special 
attention  to  the  selection  of  the  largest  plants;  and  the  yield  on  this 
was  20.8  tons  per  acre. 

2.  The  grower  thinned  32  rows  near  the  center  of  his  field,  leaving 
the  big,  thrifty  plants.  Thirty-two  rows  adjacent  were  thinned  in 
the  ordinary  way.  The  yield  on  the  former  was  at  the  rate  of  18.44 
tons  per  acre;  on  the  latter,  15.69  tons  per  acre.  This  particular 
grower  had  100  acres  in  this  field.  If  he  had  used  the  same  care  on 
the  whole  acreage  as  he  did  on  the  32  rows,  his  increased  tonnage 
would  have  been  275  tons,  which,  at  prices  current,  would  have  meant 
an  increase  of  $1925.00. 

3.  Thirty-six  rows  of  beets,  on  which  care  was  used  to  leave  the 
healthiest  and  largest  plants,  yielded  at  the  rate  of  22.06  tons  per 
acre.  Thirty-six  rows  of  beets  adjacent,  thinned  in  the  ordinary  way, 
yielded  at  the  rate  of  19.35  tons  per  acre — a  loss  of  3.61  tons  per  acre. 
The  grower  had  50  acres.  Had  he  used  the  same  care  in  thinning  the 
50  acres  as  he  did  on  36  rows,  he  would  have  harvested  174  tons  more. 


1928] 


THINNING    SUGAR    BEETS 


11 


4.  Thirty-six  rows  of  beets,  or  2.2  acres,  carefully  thinned  so  as  to 
leave  the  large  beets,  made  a  yield  of  26.59  tons  to  the  acre,  while 
6.6  acres  thinned  in  the  ordinary  way  by  contract  labor  made  a  yield 
at  21.63  tons  to  the  acre.    This  was  a  gain  of  4.96  tons  to  the  acre. 

5.  From  30  rows  of  beets,  which  were  carefully  thinned  with 
special  care  to  leave  the  big  beets,  were  taken  roots  at  the  rate  of 
21.76  tons  per  acre.  The  adjoining  30  rows,  thinned  by  contract 
labor,  yielded  at  the  rate  of  19.33  tons  per  acre.  This  is  a  gain  of 
2.43  tons  per  acre. 

6.  Twenty-four  rows  of  beets  (1.11  acres)  were  thinned  carefully 
so  as  to  leave  the  healthy  and  large"  beets ;  25  rows  adjoining  were 
thinned  by  the  regular  contractor.  The  yield  on  the  carefully  thinned 
plot  was  at  the  rate  of  27.63  tons  per  acre,  and  on  the  other  plot, 
23.32  tons  per  acre.    This  was  a  gain  of  4.31  tons  per  acre. 

7.  ''Average"  thinning  gave  a  yield  per  acre  of  13.3  tons;  thin- 
ning in  which  only  the  healthy,  large  seedlings  were  left  gave  a  yield 
per  acre  of  23.7  tons ;  and  thinning  in  which  only  the  weak  seedlings 
were  left  gave  a  yield  per  acre  of  9.2  tons. 

8.  The  grower  stopped  his  laborers  in  the  midst  of  a  thinning 
operation  and  explained  to  them  that  in  thinning  the  next  36  rows, 
they  were  to  take  pains  to  leave  the  big  beets.  As  a  check  on  these 
36  rows,  he  selected  just  beside  the  test  plot,  36  rows  which  had  been 
thinned  immediately  preceding  the  test  plot.  The  yield  per  acre  on 
the  check  plot  was  14.7  tons,  on  the  test  plot,  17.3  tons,  the  difference 
being  2.6  tons  per  acre. 

9.  The  results  of  selective  thinning  obtained  in  different  territories 
served  by  the  American  Beet  Sugar  Company  have  been  reported 
by  Mr.  A.  W.  Skuderna,  Superintendent  of  Agricultural  Research. 
They  are  summarized  in  table  4. 


TABLE  4 
Effect  of  Selective  Thinning  on  Yield 


Vigor  of  plants 
left  at  thinning 

Arkansas  Valley, 

Colorado, 
tons  to  the  acre 

Mason  City, 

Iowa, 

tons  to  the  acre 

Hector,  Minnesota, 
tons  to  the  acre 

East  Grand  Eapids, 

Minnesota, 

tons  to  the  acre 

Strong 

15  07 

12.58 

9.56 

14.44 
13.26 
10.71 

11.16 
9.36 
9.13 

15  49 

13.01 

Small 

9.42 

Thus  it  is  well  demonstrated  that  increased  yields  result  from 
leaving  the  large  seedling  at  thinning,  and  that  the  extra  cost  in  labor 
necessary  is  compensated  for  several  times  over.  There  is  no  easier 
way  to  increase  profits  from  a  beet  crop  than  that  of  leaving  the 
largest  and  healthiest  beets. 


12  CALIFORNIA  AGRICULTURAL  EXTENSION  SERVICE  [CiRC.  22 


METHODS    OF    WORK    BY    THINNERS 

Almost  all  thinning  of  beets  in  California  is  done  by  Mexicans, 
together  with  a  few  Filipinos,  Japanese,  and  Hindus.  These  workers 
use  a  short-handled  hoe,  crawling  along  the  rows  on  their  hands  and 
knees.  Usually  a  worker  takes  two  rows  at  a  time ;  each  does  his  own 
blocking  and  thinning.  Generally  speaking,  there  is  much  room  for 
improvement  in  the  method  of  work  of  thinners.  Observation  of  their 
methods  shows  many  glaring  faults,  which  should  and  can  be  cor- 
rected. Some  workers  by  carelessly  dragging  a  foot  or  knee  along  a 
row,  destroy  many  plants.  Others  tend  to  cut  too  deeply  with  the 
hoe,  removing  an  unnecessarily  large  amount  of  soil  from  the  row 
and  from  around  the  beets.  In  many  instances  a  trench  is  left  down 
the  row,  with  sharp  sides  made  by  the  cut  of  the  hoe,  and  the  young 
plants,  with  much  of  their  roots  exposed,  remain  prostrate  and 
dangling.  The  young  beet  should  not  be  left  standing  on  a  small 
block  of  earth  which  will  dry  out  rapidly  at  the  sides.  By  the  proper 
use  of  the  hoe,  the  surplus  beet  plants  and  the  weeds  are  cut  off,  and 
the  soil  and  the  desired  beets  are  left  in  their  original  position.  The 
cut  made  by  the  hoe  should  be  only  deep  enough  to  come  below  the 
crown  of  the  plants  to  be  removed. 

Many  thinned  beets  die  in  the  scorching  sun,  because,  as  related 
above,  they  have  been  left  dangling  by  a  mere  thread  of  a  root,  with 
the  soil  drawn  away  from  them  by  the  hoe.  The  plant  should  be 
disturbed  as  little  as  possible  and  kept  in  an  erect  position.  Soil 
should  be  pulled  around  the  root  of  each  beet  which  is  left  at  thinning. 
This  is  indeed  an  important  factor  in  securing  an  increased  yield. 

Some  workers  use  an  unnecessarily  wide  hoe.  It  is  true  that 
greater  speed  is  made  with  such  a  tool,  but  most  certainly  at  the 
cost  of  reduced  yield.  Closer  spacing  will  be  secured  if  the  hoe  blade 
is  not  over  six  or  seven  inches  wide.  Several  very  successful  growers 
in  the  Delta  region,  on  loose  peat  soil,  do  not  allow  a  hoe  in  the  field. 
It  is  possible,  in  this  very  loose  soil,  to  block  and  thin  with  the  hands. 
This  method  is  to  be  commended  in  soils  which  make  it  possible. 

In  the  case  of  contract  labor,  speed  is  uppermost  in  the  mind  of 
the  worker.  Almost  always,  as  a  consequence,  the  beet  crop  suffers. 
The  thinner  attempts  to  cut  out,  rather  than  pull  out,  as  many  beets 
as  possible,  and,  in  doing  so,  often  widens  the  spacing  or  cuts  too 
close  to  the  beet  which  he  wishes  to  leave.  Moreover,  he  is  making  a 
slash  with  the  hoe  ahead  of  him  in  the  row,  with  his  eye  directed 


1928]  THINNING    SUGAR    BEETS  13 

forward,  while  with  the  other  hand  he  is  blindly  feeling  his  way  in 
the  small  block  of  beets  just  left  in  an  attempt  to  remove  all  but  one 
beet  from  this  block.  In  this  operation  he  all  too  frequently  removes 
the  largest  beet,  Avhich  is  the  one  most  easily  grasped,  or  he  leaves 
''doubles." 

As  stated  above,  many  workers  attempt  to  block  and  thin  two 
rows  at  a  time.  Field  tests  demonstrate  conclusively  that  better 
stands  are  secured  when  one  row  at  a  time,  rather  than  two,  is  blocked 
and  thinned,  for  in  the  former  case,  the  worker's  attention  is  more 
concentrated  on  his  job. 

The  method  of  thinning  beets  employed  in  Europe,  in  the  Middle 
West,  and  in  the  Rocky  Mountain  States,  is  one  involving  two  distinct 
operations.  These  are  (1)  Mocking  or  spacing,  and  (2)  thinning 
proper.  Blocking  is  done  with  a  long-handled  hoe ;  thinning  is  done 
by  hand.  It  is  the  writer's  conviction  that  this  method  is  superior 
to  that  commonly  practiced  in  California.  It  has  a  tendency  to 
compel  the  thinners  to  leave  a  beet  in  the  block,  the  stand  is  usually 
more  uniform,  and  the  spacing  can  be  performed  when  the  beets  are 
still  too  small  to  be  thinned. 

The  blocking  should  precede  thinning  by  several  days.  During 
this  interval,  the  plants  cut  out  have  an  opportunity  to  wither,  thus 
making  the  blocks  more  visible.  Moreover,  in  blocking,  a  certain 
amount  of  competition  of  seedlings  is  removed,  and  the  plants  left 
standing  in  the  blocks  can  make  more  rapid  growth.  By  thinning  in 
two  operations,  each  worker  has  but  one  operation  to  think  about. 
The  blocker  can  give  his  undivided  attention  to  spacing;  the  thinner, 
working  as  he  does  without  a  hoe,  can  direct  his  attention  to  thin- 
ning each  block  and  leaving  in  it  the  largest  and  most  thrifty  beet. 
Blocking  and  thinning  in  two  operations  cost  slightly  more  than 
when  done  simultaneously,  but  the  increased  yields  more  than  com- 
pensate for  the  extra  cost.  It  will  be  a  distinct  step  forward  in 
California  beet  culture  if  the  long-handled  hoe  is  generally  adopted, 
and  thinning  is  done  in  two  distinct  operations.  Once  labor  has 
become  accustomed  to  this  method,  it  will  be  reluctant  to  go  back  to 
the  present  practice. 

DOUBLES 

When  two  beets  grow  very  close  together,  the  development  of  both 
of  them  is  often  hindered,  and  their  combined  weight  usually  does  not 
equal  the  weight  of  one  beet  left  standing  at  that  point.  In  some 
soils,  particularly  heavy  ones,  the  roots  of  doubles  coil  about  each 
other.    It  appears  that  doubles  in  the  lighter  types  of  soil  are  not  as 


14  CALIFORNIA  AGRICULTURAL  EXTENSION  SERVICE  [CiRC.  22 

undesirable  as  in  heavier  soils.  Doubles  should  be  removed  with  the 
hand ;  it  is  better  to  leave  them  than  to  attempt  their  removal  with  a 
hoe.  I\Iany  times  the  laborer  cuts  off  both  plants,  instead  of  one, 
when  he  tries  to  remove  one  of  the  doubles  with  the  hoe.  In  remov- 
ing a  double,  care  should  be  taken  to  leave  the  healthier  and  larger 
of  the  two  plants. 

SUPERVISION    OF    LABOR 

It  is  safe  to  say  that  no  single  effort  on  the  part  of  the  sugar  beet 
grower  will  bring  as  large  returns  as  the  proper'  instruction  and 
supervision  of  the  labor  at  the  time  the  crop  is  thinned.  There  should 
be  an  attempt  to  instruct  labor,  and  to  explain  definitely  how  to  thin 
and  why.  The  grower  should  not  take  it  for  granted  that  his  labor 
is  experienced.  Not  only  must  definite  instruction  be  given,  but  the 
quality  of  the  work  must  be  checked  frequently,  for  one  cannot  assume 
that  because  labor  has  been  started  right,  it  Avill  continue  as  first 
directed.  Carry  a  measuring  tape  into  the  field  and  frequently 
check  up  on  the  number  of  plants  that  are  being  left  per  100  feet 
of  row. 

The  grower  need  not  stand  over  labor  like  a  section  boss ;  and  his 
supervision  need  not  be  harsh  criticism.  Laborers  must  be  treated 
as  human  beings.  But  the  grower  must  be  in  the  field  every  day, 
and  if  possible  make  a  careful  and  actual  check  of  the  work.  Labor 
will  be  careless  and  indifferent  if  the  grower  is  careless  and  indiffer- 
ent. Labor  will  do  satisfactory  w^ork  if  it  is  properly  instructed  and 
supervised. 

Many  growers  leave  the  job  of  supervision  to  the  sugar  company 
fieldman,  who  has  many  fields  to  look  after.  Necessarily  he  cannot 
give  any  one  the  close  attention  that  the  growler  can. 

Mr.  G.  E.  Bensel,  formerly  Director  of  the  Department  of  Agri- 
cultural Research  of  the  Spreckels  Sugar  Company,  and  an  experi- 
enced beet  grower,  states :  ' '  The  thinning  is  a  very  delicate  operation, 
probably  the  most  important  of  all  operations  in  sugar  beet  culture, 
because  after  the  crop  has  been  injured  by  poor  thinning,  there  is  no 
subsequent  operation  which  can  correct  the  damage,  and  also  because 
the  final  outcome  depends  chiefly  upon  the  quality  and  quantity  of 
beets  left  in  the  field.  For  this  reason,  the  thinning  requires  the 
utmost  attention  on  the  part  of  the  grower,  his  continuous  presence 
while  this  important  work  is  being  performed  by  disinterested 
laborers,  who  are  trying  to  fulfill  the  contract  with  the  least  possible 
work,  travelling  fast  in  order  to  reach  the  end  of  the  row,  leaving 


1928]  THINNING    SUGAR    BEETS  15 

many  doubles,  and  destroying  many  properly  placed  beets,  which, 
if  they  had  remained,  would  have  materially  increased  the  yield.  I 
have  often  noticed  that  beet  growers,  in  order  to  save  a  day's  wages, 
ride  a  cultivator  or  perform  some  other  work  on  the  farm  while  a 
large  crew  of  men  are  thinning  his  crop  without  any  supervision  and 
perhaps,  in  certain  instances,  are  injuring  his  crop  to  the  extent  of 
ten  or  twenty  times  a  man's  salary. 

"Lack  of  supervision  on  the  part  of  the  grower  is  principally  due 
to  the  fact  that  he  does  not  realize  the  importance  of  the  work.  In 
most  cases  he  starts  the  crew  and  then  leaves  them  to  finish  the  work 
as  they  see  fit.  By  personal  supervision,  the  farmers  will  find  at  the 
completion  of  the  work,  that  the  time  was  well  spent,  because  they 
will  have  a  more  even  stand,  more  beets  per  acre,  fewer  doubles,  and 
fewer  weeds — all  factors  which  will  contribute  very  materially  to 
increase  the  yield  and  the  gross  return  to  the  grower." 

In  order  further  to  emphasize  the  value  of  supervision  and  better 
to  judge  whether  or  not  it  pays  in  dollars  and  cents,  let  us  cite  cases. 
With  rows  20  inches  apart,  there  are  26,136  feet  of  row  to  the  acre. 
If  the  thinners  leave  80  beets  to  100  feet  of  row,  there  will  be  20,880 
beets  to  the  acre.  If  we  assume  that  the  average  weight  of  a  beet 
is  24  ounces,  the  tonnage  with  this  stand  will  be  15.6.  If,  under  care- 
ful supervision,  the  labor  leaves  100  beets  to  100  feet  of  row  instead 
of  80,  there  would  be  26,136  beets  to  the  acre,  equivalent  to  19.6  tons. 
This  represents  a  difference  of  four  tons  to  the  acre,  the  value  of 
which  would  pay  for  considerable  supervision.  In  the  case  cited 
above,  if  the  labor  can  be  induced  to  leave  but  10  more  beets  per 
100  feet  of  row,  the  increase  resulting  would  be  approximately  two 
tons.  A  slight  calculation  will  demonstrate  to  the  grower  that  he 
can  w^ell  afford  to  spend  considerable  energy  and  money  in  order 
that  he  may  secure  a  good  thinned  stand. 

INCENTIVE    TO    THE    BEET    WORKER 

It  is  the  practice  of  many  growers  and  sugar  companies  to  stimu- 
late a  better  quality  of  labor  by  offering  bonuses  or  prizes.  These 
should  go  to  the  laborer  who  actually  performs  good  work,  not  to  the 
contractor.  In  one  beet  territory,  it  has  been  the  plan  of  many 
growers  to  insert  in  the  contract  a  bonus  clause,  which  provides  that 
the  grower  will  pay,  in  addition  to  the  regular  basic  rate,  an  extra 
sum  per  acre  for  each  ton  more  than  an  average  yield  of  a  certain 
specified  number  of  tons  per  acre.  This  requires  the  determination  of 
the  percentage  of  stand  before  and  after  thinning,  but  the  additional 
effort  is  justified  by  the  better  stand  that  finally  remains. 


16  CALIFORNIA  AGRICULTURAL  EXTENSION  SERVICE  [CiRC.  22 


ACKNOWLEDGMENTS 

The  writer  of  this  circular  wishes  to  acknowledge  the  use  of 
material  that  has  appeared  in  publications  of  the  Great  Western 
Sugar  Company,  with  which  organization  he  was  at  one  time  associ- 
ated. He  also  wishes  to  express  appreciation  to  those  who  read  the 
circular  in  manuscript  form  and  gave  criticisms  and  suggestions, 
which,  it  is  believed,  will  make  the  publication  more  useful  to  growers 
in  the  various  sugar  beet  districts  of  California.  Those  who  have 
extended  this  service  and  courtesy  are  as  follows:  G.  E.  Bensel, 
formerly  Director,  Department  of  Agricultural  Research,  Spreckels 
Sugar  Company;  E.  Carsner,  Sugar  Plant  Investigations,  U.  S. 
Department  of  Agriculture ;  Raymond  Ellis,  Assistant  Farm  Advisor, 
Orange  County;  F.  H.  Johnson,  Manager,  Union  Sugar  Company; 
C.  T.  Lund,  Agricultural  Superintendent,  Holly  Sugar  Corporation; 
S.  E.  Miller,  Resident  Manager,  Spreckels  Sugar  Company;  J.  W. 
Rooney,  Manager,  American  Beet  Sugar  Company ;  and  R.  H.  Tall- 
man,  Agricultural  Superintendent,  Holly  Sugar  Corporation;  and 
Professors  R.  L.  Adams,  John  W.  Gilmore,  H.  A.  Jones,  and  Thomas 
Mayhew,  all  of  the  College  of  Agriculture,  University  of  California. 


